scholarly journals Using Photoactive N-Heterocyclic Carbenes Monolayers to Identify the Influence of Surface Proximity on Photoswitching Activity

2020 ◽  
Author(s):  
Shahar Dery ◽  
Israel Alshanski ◽  
Evgeniy Mervinetsky ◽  
Daniel Feferman ◽  
Shlomo Yitzchaik ◽  
...  
Keyword(s):  
Surface Potential ◽  
Self Assembly ◽  
Functional Materials ◽  
Imidazole Ring ◽  
Structural Flexibility ◽  
Vertical Orientation ◽  
Order Of Magnitude ◽  
Adsorption Geometry ◽  
Photoinduced Changes ◽  
The Impact

<p>Self-assembly of photoresponsive molecules is a robust technology for reversibly tuning the chemical and electronic properties of functional materials. In most systems the photoactive group is separated from the surface by a spacer and thus the photo-responsiveness does not benefit from interactions with the metal. Herein, the impact of metal photoactive-group interactions on photoswitchability and surface potential were probed by self-assembly of N-heterocyclic carbene molecules (NHCs) that were functionalized with stilbene group directly on their imidazole ring. Stilbene-NHCs that were adsorbed on weakly interacting Au surface accumulated a vertical orientation, as identified by FTIR measurements. This positioning enabled structural flexibility and high photoisomerization efficiency that induced reversible changes in surface potential. Stilbene-NHCs that were anchored on Pt film accumulated flat-lying adsorption geometry due to strong metal-adsorbate interactions. These interactions limited the structural flexibility of the stilbene groups and induced deteriorated photoswitchability that led to lower photoinduced changes in surface potential. While stronger metal-adsorbate interactions hindered the photo-induced isomerization yield of stilbene, these interactions prompted the <i>cis</i>-to-<i>trans</i> thermal-induced isomerization rate, which was an order of magnitude higher on Pt than on Au. </p>

scholarly journals Using Photoactive N-Heterocyclic Carbenes Monolayers to Identify the Influence of Surface Proximity on Photoswitching Activity

2020 ◽  
Author(s):  
Shahar Dery ◽  
Israel Alshanski ◽  
Evgeniy Mervinetsky ◽  
Daniel Feferman ◽  
Shlomo Yitzchaik ◽  
...  
Keyword(s):  
Surface Potential ◽  
Self Assembly ◽  
Functional Materials ◽  
Imidazole Ring ◽  
Structural Flexibility ◽  
Vertical Orientation ◽  
Order Of Magnitude ◽  
Adsorption Geometry ◽  
Photoinduced Changes ◽  
The Impact

<p>Self-assembly of photoresponsive molecules is a robust technology for reversibly tuning the chemical and electronic properties of functional materials. In most systems the photoactive group is separated from the surface by a spacer and thus the photo-responsiveness does not benefit from interactions with the metal. Herein, the impact of metal photoactive-group interactions on photoswitchability and surface potential were probed by self-assembly of N-heterocyclic carbene molecules (NHCs) that were functionalized with stilbene group directly on their imidazole ring. Stilbene-NHCs that were adsorbed on weakly interacting Au surface accumulated a vertical orientation, as identified by FTIR measurements. This positioning enabled structural flexibility and high photoisomerization efficiency that induced reversible changes in surface potential. Stilbene-NHCs that were anchored on Pt film accumulated flat-lying adsorption geometry due to strong metal-adsorbate interactions. These interactions limited the structural flexibility of the stilbene groups and induced deteriorated photoswitchability that led to lower photoinduced changes in surface potential. While stronger metal-adsorbate interactions hindered the photo-induced isomerization yield of stilbene, these interactions prompted the <i>cis</i>-to-<i>trans</i> thermal-induced isomerization rate, which was an order of magnitude higher on Pt than on Au. </p>

The Influence of Surface Proximity on Photoswitching Activity of Stilbene-Functionalized N-Heterocyclic Carbene Monolayers

2021 ◽  
Author(s):  
Shahar Dery ◽  
Israel Alshanski ◽  
Evgeniy Mervinetsky ◽  
Daniel Feferman ◽  
Shlomo Yitzchaik ◽  
...  
Keyword(s):  
Self Assembly ◽  
Crucial Role ◽  
Functional Materials ◽  
Adsorption Geometry ◽  
Surface Proximity

Self-assembly of photo-responsive molecules is a robust technology for reversibly tuning the properties of functional materials. Herein, we probed the crucial role of surface-adsorbate interactions on the adsorption geometry of...

scholarly journals Shaping colloidal bananas to reveal biaxial, splay-bend nematic, and smectic phases

Science ◽  
2020 ◽  
Vol 369 (6506) ◽  
pp. 950-955
Author(s):  
Carla Fernández-Rico ◽  
Massimiliano Chiappini ◽  
Taiki Yanagishima ◽  
Heidi de Sousa ◽  
Dirk G. A. L. Aarts ◽  
...  
Keyword(s):  
Phase Behavior ◽  
Self Assembly ◽  
Colloidal Particles ◽  
Functional Materials ◽  
Building Blocks ◽  
Develop Model ◽  
Smectic Phases ◽  
Particle Level ◽  
Nematic Phases ◽  
The Impact

Understanding the impact of curvature on the self-assembly of elongated microscopic building blocks, such as molecules and proteins, is key to engineering functional materials with predesigned structure. We develop model “banana-shaped” colloidal particles with tunable dimensions and curvature, whose structure and dynamics are accessible at the particle level. By heating initially straight rods made of SU-8 photoresist, we induce a controllable shape deformation that causes the rods to buckle into banana-shaped particles. We elucidate the phase behavior of differently curved colloidal bananas using confocal microscopy. Although highly curved bananas only form isotropic phases, less curved bananas exhibit very rich phase behavior, including biaxial nematic phases, polar and antipolar smectic-like phases, and even the long-predicted, elusive splay-bend nematic phase.

An Analytical Modeling and Performance Analysis of Graded Work Function Gate Recessed Channel SOI-MOSFET

2019 ◽  
Vol 9 (4) ◽  
pp. 504-511
Author(s):  
Sikha Mishra ◽  
Urmila Bhanja ◽  
Guru Prasad Mishra
Keyword(s):  
Analytical Model ◽  
Surface Potential ◽  
Threshold Voltage ◽  
Silicon On Insulator ◽  
Junction Depth ◽  
Short Channel ◽  
Soi Mosfet ◽  
Minimum Surface ◽  
Recessed Channel ◽  
The Impact

Introduction: A new analytical model is designed for Workfunction Modulated Rectangular Recessed Channel-Silicon On Insulator (WMRRC-SOI) MOSFET that considers the concept of groove gate and implements an idea of workfunction engineering. Methods: The impact of Negative Junction Depth (NJD) and oxide thickness (tox) are analyzed on device performances such as Sub-threshold Slope (SS), Drain Induced Barrier Lowering (DIBL) and threshold voltage. Results: The results of the proposed work are evaluated with the Rectangular Recessed Channel-Silicon On Insulator (RRC-SOI) MOSFET keeping the metal workfunction constant throughout the gate region. Furthermore, an analytical model is developed using 2D Poisson’s equation and threshold voltage is estimated in terms of minimum surface potential. Conclusion: In this work, the impact of Negative Junction Depth (NJD) on minimum surface potential and the drain current are also evaluated. It is observed from the analysis that the analog switching performance of WMRRC-SOI MOSFET surpasses RRC-SOI MOSFET in terms of better driving capability, high Ion/Ioff ratio, minimized Short Channel Effects (SCEs) and hot carrier immunity. Results are simulated using 2D Sentaurus TCAD simulator for validation of the proposed structure.

Pound Wise and Penny Foolish? Weight Loss and The Dynamics of Health Care Spending

2011 ◽  
Vol 14 (2) ◽  
Author(s):  
Thomas G Koch
Keyword(s):  
Weight Loss ◽  
Cost Savings ◽  
Cost Effective ◽  
Economic Consequences ◽  
Health Care Spending ◽  
Order Of Magnitude ◽  
Dynamic Measures ◽  
The Cost ◽  
The Impact ◽  
The Relationship

Current estimates of obesity costs ignore the impact of future weight loss and gain, and may either over or underestimate economic consequences of weight loss. In light of this, I construct static and dynamic measures of medical costs associated with body mass index (BMI), to be balanced against the cost of one-time interventions. This study finds that ignoring the implications of weight loss and gain over time overstates the medical-cost savings of such interventions by an order of magnitude. When the relationship between spending and age is allowed to vary, weight-loss attempts appear to be cost-effective starting and ending with middle age. Some interventions recently proven to decrease weight may also be cost-effective.

Unique Functional Materials Derived from β-Amino Acid Oligomers

2017 ◽  
Vol 70 (2) ◽  
pp. 126 ◽  
Author(s):  
Mark P. Del Borgo ◽  
Ketav Kulkarni ◽  
Marie-Isabel Aguilar
Keyword(s):  
Amino Acid ◽  
Drug Design ◽  
Self Assembly ◽  
Functional Materials ◽  
Bioactive Molecules ◽  
Peptide Drug ◽  
New Materials ◽  
Amino Acid Oligomers

The unique structures formed by β-amino acid oligomers, or β-peptide foldamers, have been studied for almost two decades, which has led to the discovery of several distinctive structures and bioactive molecules. Recently, this area of research has expanded from conventional peptide drug design to the formation of assemblies and nanomaterials by peptide self-assembly. The unique structures formed by β-peptides give rise to a set of new materials with altered properties that differ from conventional peptide-based materials; such new materials may be useful in several bio- and nanomaterial applications.

scholarly journals Diketopiperazine Gels: New Horizons from the Self-Assembly of Cyclic Dipeptides

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3376
Author(s):  
Marco Scarel ◽  
Silvia Marchesan
Keyword(s):  
Drug Discovery ◽  
Enzymatic Hydrolysis ◽  
Self Assembly ◽  
Biological Activities ◽  
Functional Materials ◽  
The Self ◽  
Cyclic Dipeptides ◽  
New Horizons ◽  
Concise Review

Cyclodipeptides (CDPs) or 2,5-diketopiperazines (DKPs) can exert a variety of biological activities and display pronounced resistance against enzymatic hydrolysis as well as a propensity towards self-assembly into gels, relative to the linear-dipeptide counterparts. They have attracted great interest in a variety of fields spanning from functional materials to drug discovery. This concise review will analyze the latest advancements in their synthesis, self-assembly into gels, and their more innovative applications.

scholarly journals Nanostructure, Self-Assembly, Mechanical Properties, and Antioxidant Activity of a Lupin-Derived Peptide Hydrogel

Biomedicines ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 294
Author(s):  
Raffaele Pugliese ◽  
Anna Arnoldi ◽  
Carmen Lammi
Keyword(s):  
Mechanical Properties ◽  
Antioxidant Activity ◽  
Self Assembly ◽  
Antioxidant Activities ◽  
Functional Materials ◽  
Cd Spectroscopy ◽  
Beneficial Effects ◽  
Naturally Occurring ◽  
New Research ◽  
Peptide Hydrogel

Naturally occurring food peptides are frequently used in the life sciences due to their beneficial effects through their impact on specific biochemical pathways. Furthermore, they are often leveraged for applications in areas as diverse as bioengineering, medicine, agriculture, and even fashion. However, progress toward understanding their self-assembling properties as functional materials are often hindered by their long aromatic and charged residue-enriched sequences encrypted in the parent protein sequence. In this study, we elucidate the nanostructure and the hierarchical self-assembly propensity of a lupin-derived peptide which belongs to the α-conglutin (11S globulin, legumin-like protein), with a straightforward N-terminal biotinylated oligoglycine tag-based methodology for controlling the nanostructures, biomechanics, and biological features. Extensive characterization was performed via Circular Dichroism (CD) spectroscopy, Fourier Transform Infrared spectroscopy (FT-IR), rheological measurements, and Atomic Force Microscopy (AFM) analyses. By using the biotin tag, we obtained a thixotropic lupin-derived peptide hydrogel (named BT13) with tunable mechanical properties (from 2 to 11 kPa), without impairing its spontaneous formation of β-sheet secondary structures. Lastly, we demonstrated that this hydrogel has antioxidant activity. Altogether, our findings address multiple challenges associated with the development of naturally occurring food peptide-based hydrogels, offering a new tool to both fine tune the mechanical properties and tailor the antioxidant activities, providing new research directions across food chemistry, biochemistry, and bioengineering.

scholarly journals Ice Coverage Induced by Depositing a Water Drop onto the Supercooled Substrate at Extreme Low Vapor Pressure

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 691
Author(s):  
Yugang Zhao ◽  
Zichao Zuo ◽  
Haibo Tang ◽  
Xin Zhang
Keyword(s):  
Vapor Pressure ◽  
Substrate Temperature ◽  
Water Drop ◽  
Industrial Processes ◽  
Aircraft Icing ◽  
Ice Coverage ◽  
Fundamental Understanding ◽  
Order Of Magnitude ◽  
The Impact ◽  
Kinetics Of

Icing/snowing/frosting is ubiquitous in nature and industrial processes, and the accretion of ice mostly leads to catastrophic consequences. The existing understanding of icing is still limited, particularly for aircraft icing, where direct observation of the freezing dynamics is inaccessible. In this work, we investigate experimentally the impact and freezing of a water drop onto the supercooled substrate at extremely low vapor pressure, to mimic an aircraft passing through clouds at a relatively high altitude, engendering icing upon collisions with pendant drops. Special attention is focused on the ice coverage induced by an impinging drop, from the perimeter pointing outward along the radial direction. We observed two freezing regimes: (I) spread-recoil-freeze at the substrate temperature of Ts = −15.4 ± 0.2 °C and (II) spread (incomplete)-freeze at the substrate temperature of Ts = −22.1 ± 0.2 °C. The ice coverage is approximately one order of magnitude larger than the frozen drop itself, and counterintuitively, larger supercooling yields smaller ice coverage in the range of interest. We attribute the variation of ice coverage to the kinetics of vapor diffusion in the two regimes. This fundamental understanding benefits the design of new anti-icing technologies for aircraft.

scholarly journals Virus-Like Particles Produced Using the Brome Mosaic Virus Recombinant Capsid Protein Expressed in a Bacterial System

2021 ◽  
Vol 22 (6) ◽  
pp. 3098
Author(s):  
Aleksander Strugała ◽  
Jakub Jagielski ◽  
Karol Kamel ◽  
Grzegorz Nowaczyk ◽  
Marcin Radom ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Mosaic Virus ◽  
Capsid Protein ◽  
Self Assembly ◽  
Environmental Changes ◽  
Expression System ◽  
Brome Mosaic Virus ◽  
Virus Like Particles ◽  
Assembly Principles ◽  
The Impact

Virus-like particles (VLPs), due to their nanoscale dimensions, presence of interior cavities, self-organization abilities and responsiveness to environmental changes, are of interest in the field of nanotechnology. Nevertheless, comprehensive knowledge of VLP self-assembly principles is incomplete. VLP formation is governed by two types of interactions: protein–cargo and protein–protein. These interactions can be modulated by the physicochemical properties of the surroundings. Here, we used brome mosaic virus (BMV) capsid protein produced in an E. coli expression system to study the impact of ionic strength, pH and encapsulated cargo on the assembly of VLPs and their features. We showed that empty VLP assembly strongly depends on pH whereas ionic strength of the buffer plays secondary but significant role. Comparison of VLPs containing tRNA and polystyrene sulfonic acid (PSS) revealed that the structured tRNA profoundly increases VLPs stability. We also designed and produced mutated BMV capsid proteins that formed VLPs showing altered diameters and stability compared to VLPs composed of unmodified proteins. We also observed that VLPs containing unstructured polyelectrolyte (PSS) adopt compact but not necessarily more stable structures. Thus, our methodology of VLP production allows for obtaining different VLP variants and their adjustment to the incorporated cargo.

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